There is a spatial offset of about 2 arcsec in the X direction between images formed from long wavelength (LW) band emission lines, and those formed from short wavelength (SW) band emission lines.

If you are rastering over a solar feature with the 1" slit, then the feature will be seen first in the SW band and then, 2 exposures later, will be seen in the LW band. Thus the SW band image is offset 2" to solar-west of the LW band image.

Some discussion of this is given in Young et al. (2007).

The reason for this offset lies in the fact that the two CCD images arise from different halves of the primary mirror. The focal points of the two mirror halves could thus be different.

A key consequence of this offset is that images from the different CCDs taken with sit-and-stare observations can not be directly compared since they show different parts of the Sun.